import { ReduceArrayIterator, ReduceArrayLikeIterator, ReduceObjectIterator, ReduceStringIterator, WithNullable } from './types';
export interface Reduce {
    <T, R>(collection: WithNullable<T[]>, iteratee: ReduceArrayIterator<T, R>, initialValue: R): R;
    <R>(collection: WithNullable<string>, iteratee: ReduceStringIterator<R>, initialValue: R): R;
    <T, R>(collection: WithNullable<ArrayLike<T>>, iteratee: ReduceArrayLikeIterator<T, R>, initialValue: R): R;
    <T extends object, R>(collection: WithNullable<T>, iteratee: ReduceObjectIterator<T, R>, initialValue: R): R;
    <T>(collection: WithNullable<T[]>, iteratee?: ReduceArrayIterator<T, T>): T | undefined;
    (collection: WithNullable<string>, iteratee?: ReduceStringIterator<string>): string | undefined;
    <T>(collection: WithNullable<ArrayLike<T>>, iteratee?: ReduceArrayLikeIterator<T, T>): T | undefined;
    <T extends object>(collection: WithNullable<T>, iteratee?: ReduceObjectIterator<T, T[keyof T]>): T[keyof T] | undefined;
}
/**
 * 创建 reducer 函数
 *
 * @private
 * @param dir 迭代方向
 * @returns reduce 方法
 */
declare function createReduce(dir: 1 | -1): Reduce;
export default createReduce;